Header

Objective Reviews & Commentary - An Engineer's Perspective

November 9, 2011

X-Fi USB DAC

INTRO: I’ve been testing portable reasonably priced USB partly in the hope of finding one that’s a good match for pairing with my 02 headphone amp. The C-Media based inexpensive USB DACs from FiiO, Turtle Beach and Syba were all disappointing. What happens if you spend a bit more money ($35) for a similar DAC from one of the biggest names in PC audio? Creative offers the X-Fi Go Pro as their “thumb drive” portable DAC. How does it measure up to the C-Media DACs already reviewed?

CREATIVE SOUND BLASTER X-FI GO! PRO THX TRUESTUDIO SB1290: For all the money Creative spends on marketing, and after Apple elegantly slaughtered them in the portable player market, one might think Creative could at least adopt user-friendly product names. I think they only left out “Turbo”, “Audiophile” and “Ultra”. Fortunately the DAC is simpler than the convoluted marketing mess. There’s a whole range of X-Fi products, but I’m just going to call this one the “X-Fi” for simplicity. It’s a lot like the Syba USB DAC with an integrated USB plug, 3.5mm headphone/line out, microphone jack, LED, and nothing else. It does, however, come with a USB extension cable which is handy for accessing recessed USB ports or where the DAC might block other ports. And it has a cover for the USB plug making it look a lot like a Zippo cigarette lighter—more clever Creative marketing targeting old school smokers.

OOOOH THX! Once upon a time THX was a rigorous certification process reserved for some of the best home theater gear. THX amplifiers, for example, were required to deliver certain levels of power, over a wide bandwidth, at low distortion, with all channels driven. Now, sadly, it seems THX is just a logo and/or a software license that manufactures buy to slap on most anything. THX certified wine opener anyone? For the X-Fi it’s about the supplied software rather than the hardware. THX has put their name on a suite of me-too digital audio processing that’s not very different than similar products from SRS Labs, Dolby, and many others including the stuff Creative did on their own years ago. They’re just DSP routines that alter your music in assorted artificial ways. Some might find it useful—especially for gaming or movies with headphones. These sorts of DSP effects, to my ears, nearly always sound cheesy and artificial much like the “cathedral” mode on your home A/V receiver. The THX licensed DSP is is part of the bloatware Creative wants you to install on your PC and has nothing to do with the DAC hardware itself.

BLOATWARE SKIPPED: The last time I installed Creative software on my PC it wrecked all sorts of havoc. It’s even worse than iTunes. Creative’s massive install took over file associations, became the default media player, installed various video CODECs that broke other CODECs, tried to index my music collection and promptly locked up, etc. With Creative having already burned that bridge with me I simply used the X-Fi with native Windows drivers.

WINDOWS INSTALLATION & 24 Bit? The X-Fi installed smoothly in both XP and Windows 7 (minus THX DSP, 3D effects, etc.) without needing any third party drivers. Windows 7 reported it as a “Sound Blaster X-Fi Go! Pro”. Only one sample rate is available, 44100, but interestingly there’s a choice for 16 or 24 bits. Is the X-Fi really capable of 24 bit operation? If so that would be a significant plus as it allows using the PC (or player software) volume control and still, in theory, maintain close to 16 bit resolution to the DAC.

SUBJECTIVE SOUND QUALITY: Running the X-Fi into my 02 headphone amp the sound quality was good with no obvious problems. There was, however, some audible hiss. Connecting headphones directly the results depended on which headphones. My DT770 Pro 80s sounded fairly good, there was not enough power for my HD650s, and my UE SuperFi 5s sounded pretty bad and also revealed audible hiss.

MEASUREMENT SUMMARY: The overall results are substantially better than the C-Media offerings and generally respectable for a $35 DAC. The weak areas are noise, low level linearity, low frequency roll off into 32 ohms, and a somewhat high output impedance. I would not use the X-Fi with any headphones under 60 ohms if you want the best sound quality. It also lacks enough power for a lot of high impedance headphones. I ran several tests with both the 16 and 24 bit modes and could not detect any difference. The letter grades range from A to F where A is excellent and F is Fail (unacceptable):

O2 COMPANION: Used with an amp like the O2 with its own volume control, the X-Fi is a reasonable DAC with very flat frequency response, relatively low distortion and very low jitter. If you leave the PC/software volume control at maximum it has enough dynamic range to be quiet enough in most applications. If you want to use software volume controls, however, you might hear some noise in some circumstances.

BOTTOM LINE: The X-Fi Go performs vastly better than any of the three C-Media DACs I’ve tested. It gives the UCA202 a good challenge with similar distortion and even lower jitter while being significantly more portable. The downsides are higher noise, some low level linearity error, and not being suitable for many headphones under 60 ohms or any balanced armature IEMs. Used to drive a headphone amp, or powered speakers, the X-Fi makes a decent DAC—especially if a bit of noise under some conditions doesn’t bother you. Just don’t be fooled into thinking it supports 24 bit operation.

FREQUENCY RESPONSE: The frequency response with a 10K load (such as a headphone amp) was excellent being down only about 0.4 dB at 20 Khz with none of the filter-related ripple seen in the C-Media DACs. With a 33 ohm load, typical of portable headphones, it’s not so good. The X-Fi is –3 dB at 30 hz which is likely audible. With 16 ohm headphones it would be even worse. This indicates a capacitor coupled output with a cap that’s too small and is unfortunate. But used with a decent headphone amp (or to feed a powered audio system or speakers) the X-Fi is looking great so far:

THD+N vs OUTPUT 1 Khz 16 & 24 BIT MODES: This test starts at 10 mV (around – 40 dBFS) where noise dominates the measurement. The yellow line is with a 10K load and the X-Fi hits almost 1 volt with distortion at only 0.007%. This is a bit lower output than many USB DACs and well below the Redbook standard of 2 Vrms. In theory, 24 bit operation should lower noise and distortion at low levels. Repeating the test with the X-Fi supposedly running at 24 bits as shown by the red trace you can see it’s identical. So, at least for 1 khz THD+N vs Output level, there’s no benefit to 24 bits with the X-Fi. Into 33 ohms distortion is slightly higher but still impressively low. But maximum output is only about 750 mV due to the output impedance (more on that later). The second graph shows the UCA202 and Micro II for comparison (note the horizontal scales are different):

THD+N 100 hz 0 dBFS & OUTPUT IMPEDANCE: With the PC volume at maximum, and a 0 dBFS input, the X-Fi produces about 1 Vrms at very low distortion (shown in yellow). The harmonics are below the magic –80 dB threshold. Even the ultrasonic components are below –80 dB. With a 15 ohm load, the output drops to 0.65 Vrms indicating an output impedance of 7.8 ohms at 100hz. Part of that is the output capacitor. At 1 khz it’s slightly better at 7.1 ohms. This is a marginally high output impedance and is similar to the iPod Touch 3G. Following the “1/8th Rule” the X-Fi should ideally only be used with headphones that are 60 ohms or higher. It’s an especially poor match for Balanced Armature IEMs such as Etymotic, Shure, Ultimate Ears, Westones, etc. The output impedance, and capacitor coupled output, explains why my Ultimate Ears didn’t sound quite right. But, just like the frequency response above, used with a headphone amp the X-Fi will work reasonably well:

THD+N vs FREQUENCY: Here’s the THD+Noise plotted from 20 hz to 20 Khz into 10K (yellow) at 775 mV (0 dBu) and 33 ohms (blue). The 10K plot is impressively flat and entirely below 0.01% which is very good performance for such a small inexpensive DAC. It’s similar to the UCA202 up to 5Khz, and notably better above 5 Khz. Into 33 ohms you can see the effect of the electrolytic output capacitor increasing distortion at low frequencies and the amp apparently doesn’t like to drive low impedances above 13 Khz (it was likely clipping). So, once again, the X-Fi does fairly well if it’s driving an amp, but not so well driving headphones. The second graph shows the UCA202 and Micro II for comparison:

SMPTE IMD 10K: The X-Fi does very well here with everything around –90 dB or lower (please ignore the errors in the caption):

SMPTE IMD 33 OHMS: Even into 33 ohms, the X-Fi still does fairly well. The output capacitor is causing some trouble as can be seen by the 2nd harmonic at 120 hz just above –70 dB but that’s relatively benign THD. The IMD is still extremely low:

CCIF IMD 44 Khz 10K: The X-Fi also does well here for an inexpensive DAC into 10K. It’s particularly amazing the side bands to the high frequency signals are below –100 dB! The overall result, due to the higher difference component at 1 Khz, is not as good as the UCA202 but they’re very close. They’re both massively better than any of the C-Media DACs such as the FiiO D5 shown in the third graph for comparison:

CCIF IMD 44 Khz 33 Ohms: The X-Fi also does well here driving 33 ohms and very similar to the result above into 10K:

NOISE & LINEARITY: The X-Fi is a bit disappointing for noise at about –89 dBu A-Weighted and 50 uV of raw noise into most any load. This is no better than the $12 Syba DAC. It’s also slightly worse than average for linearity with a 1.5 dB error but that’s not likely to be audible and is still better than the UCA202’s error. I repeated this test operating (supposedly) at 24 bits and got the same result. Consistent with the distortion sweep, it’s apparent the supposed “24 bit” mode is just just creative marketing—pardon the pun. The X-Fi, in either mode, falls well short of of the theoretical 96 dB total dynamic range for 16 bits. The raw dynamic range is 1V/50uV or only 86 dB which yields an Effective Number Of Bits (ENOB) of only 14 bits. This is a bit noisier than even the UCA202 which already isn’t especially quiet (shown in the second graph for comparison). If you plan to use the X-Fi by itself, or use a software volume control with an external amp, you will hear some hiss under some circumstances:

JITTER: Here’s the spectrum from the dScope’s J-Test for jitter. The two things to look for are the number and level of symmetrical sidebands and the “spread” at the base of the 11025 hz signal. The second graph is UCA202’s jitter for comparison. The X-Fi does a significantly better job all the way around. The sidebands are lower in level and the spread is significantly less. This is excellent jitter performance for a cheap USB DAC:

24 BIT OPERATION: The X-Fi reports to Windows supporting 24 bit operation but no matter what I tried I couldn’t get anything but around 14-15 bit performance from it. Perhaps the driver is sending 24 bits over USB but the X-Fi Go might be simply discarding the 8 least significant bits or otherwise is unable to do anything with them. That’s a disappointing result and some might argue deceptive. If the X-Fi really is receiving 24 bits all the way to the DAC it might be the DAC and analog performance are poor enough they’re masking any benefit. But even if that’s the case, I would still expect to see lower THD at low input levels from reduced quantization distortion and I did not.

RESAMPLING: Creative has a reputation for re-sampling 44 Khz to something else—either on the PC side or in their hardware. I didn’t see any signs of that with the X-Fi Go. It only supports 44 Khz and if that wasn’t its native sampling frequency you would expect whatever that is (i.e. 48 Khz) would be reported to Windows. In addition you can see a 44 khz component in the spectrum graphs indicating that’s what the DAC is really running at.

TECH COMMENTS: Used to drive an amp like the O2, powered speakers, or other gear with a line input, the X-Fi Go! is a decent DAC with the exception of mediocre signal-to-noise numbers. If you leave the software volume at maximum and control the volume from the amp/speakers/etc. it should have enough dynamic range for most applications. I put it slightly ahead of the Behringer UCA202 in most regards. The maximum output is a bit limited but most amps should still have enough gain. I would not recommend it to drive headphones under 60 ohms and especially not balanced armature IEMs. It also does not have enough output for a lot of higher impedance headphones including the popular Sennheiser HD600/650.

50
comments:

I assume the volume on the O2 was at a level were full-scale music output would end up at comfortable (or loud) levels, not hearing damage territory. In any case, those are good results.

It's a real shame though that you didn't expand on the software a bit. A good system-wide (as opposed to application-specific) EQ is hard to find, and it would be interesting to see the FR curves of its bands. Also, subjective commentary on how the HRTF headphone effect works would be nice too, since many people chose to listen with effects, and again, something that works well and applies system-wide (affecting all programs like the browser, video players etc) is hard to find.

And a small question: Is the microphone input "just" a microphone input or does it accept line-level signals too?

To verify that it is 16 bit, you should measure the THD+N at not 0dBFS but maybe somewhere -16-20dBFS. Use foobar or something like it to know exactly. There should be a difference between 16 and 24 bit.

Also please calculate ENOB. -89dB THD+N means ~14.5 bit performance, so it is like a 14.5 bit DAC with a perfect analog circuit. Changing it to 24 bit wont make a difference, because (it seems)the analog has the bottleneck in this case. If you change output with 2 or more bits, than the 24 bit output can be better than 16 bit http://en.wikipedia.org/wiki/Effective_number_of_bits

Also you are just awesome, doing this articles. Nobody even tried this.

@tszaboo the plot above of THD vs Output starts off at around -40 dBFS and ramps up to 0 dBFS so I did test around -20 dBFS as you suggest. The two plots, taken at 16 and 24 bits, are virtually identical. I also tried playing back various files recorded at various levels in Foobar in both Win 7 and XP and measured the noise floor and distortion. There was no change between 16 and 24 bit modes.

It's possible the noise floor is preventing seeing any benefit from 24 bit mode, but I would think you would still see *some* difference at some levels in the THD from quantization distortion, etc. But there is no difference. Regardless of why, the 24 bit mode for the X-Fi is completely useless and offers zero benefit that I can find.

@Ferongr, the hiss from the X-Fi was only obvious either with highly sensitive headphones directly connected to it, or with the amp volume up where it might be when listening to say the quiet portion of a wide dynamic range recording. Listening to typical compressed pop recordings it's not likely to be an issue.

I won't install Creative software. I've just had too many bad experiences with it and it typically doesn't uninstall cleanly. I usually "sandbox" ill behaved software inside a virtual machine for evaluation. But, unfortunately, trying to run audio tests of a USB sound device from a virtual machine presents other problems as there's no direct access to the hardware.

@NwAvGuy You are absolutely right. The quantization noise is somewhere -96dB@16 bit, 24 wont make any difference this case.This DAC has so big harmonic distortion, and it is still better than the others... I'm not impressed by the market.

I can only support you in you decision no to contaminate your computer with Creative's drivers. I've had my fair share of problems with them too - in one case their update process broke a working installation completely... If at all uses I think the native driver is the only way for creative.

@Ferongr, the problem is the real-time nature of audio streams. You probably don't notice a few dropped frames in a virtualized webcam stream but any glitches can really mess up audio measurements with the dScope. It has to be a bit-accurate stream. I haven't tried Sandboxie specifically, but adding a layer between any 16/44 uncompressed audio application and the operating system usually creates some problems when you're trying to measure the ultimate performance of USB 1.1 PC audio hardware.

An interesting thing related to generic audio drivers is that I've had them come with enhancements anyway but each device I've used has been DIFFERENT in terms of the enhancements that Windows put in there by default. Did you check if Microsoft pushed some stuff that Creative had fed them? Click on the enhancements tab... which isn't always present with every audio device I've used.

Also, in the past I've had some luck with less hiss by turning the mic's gain boost off (in Windows) and ensuring that Windows doesn't have it setup to be listened to. You never know what affects what or what's on by default because some of the vendors feed Microsoft extra stuff that creeps in anyway.

Unless I am completely mistaken, that is how Microsoft wants it to work. Companies give them a driver, they certify it and include it in the OS. Alternatively, they can offer their own driver. Many drivers included in an OS won't be MS developed from scratch.

____Unrelated side note: I noticed I mangled my last sentence in a previous comment...

is there a reason as to why we're looking for a USB DAC when you've already determined that the Fiio E7 measures superbly? the weakness of the E7 was the output power, but since we're looking for a O2 companion, wouldn't the E7 + O2 be the combination we're looking for?

Or is it the case that we're trying to find something cheaper than the E7?

Good review. I use one of these for super-portable carry, surprised at how decent it is for the money. Nothing spectacular, but not assaulting to the ears either as many at this price-point are. Sent several gaming buddies this way, all are pleased.

Re: virtual machine sandboxing - there are VMs that allow assignment of devices to the VM directly. Also, you can just create an install of Win 7 in a VHD and native boot to it, giving a clean and isolated environment. When done, or when it gets clobbered by ill-behaving software, just roll it back in seconds from a differencing VHD. I use this *constantly*.

Agree re: creative software and "drivers"/drivers. Their SW team is a walking disaster.

@akgk171/DetLevCM, I believe I did look for "enhancement" options in the properties dialog and I don't remember seeing any. Sound devices that conform to the USB Audio 1.x standard do NOT require Microsoft include a third party driver in the OS. That's the whole idea behind the standard. The USB standard provides some support for alternate features depending on what the device reports to the operating system when it's discovered. You can find the 1998 standard here:

http://www.usb.org/developers/devclass_docs/audio10.pdf

There's also a much newer USB Audio 2.0 standard that supports true high speed operation over USB 2.0 and consequently higher sampling rates and more channels of simultaneous audio. But only the newest operating systems have native Audio 2.0 support and few home consumer devices are using it.

@firev1, the "X-Fi HD" is a very different product from the X-Fi Go. In theory it should perform better but some have said it doesn't support native 44 Khz sampling rates and forces the operating system to resample nearly all music (44 Khz) to 48 Khz which is bad form for a DAC.

@heycarnut, Glad you liked the review and you are reasonably happy with your X-Fi Go. VMware allows assigning USB devices to a VM, but in my experience it causes problems with some USB audio devices. They appear to work OK for casual use but there are glitches in the bit stream--especially when trying to use the dScope software in a VM to directly interface with the sound hardware. It may be related to the VM running a virtual CPU and/or the overhead of the VM engine, rather than the USB interface directly. But I can safely say even on a Core i7 with lots of RAM I've had problems. And, from what I know, VirtualBox has inferior USB support to VMware but I haven't tried it. Good point about booting to a VHD and being able to later roll it back but I don't have such an environment set up.

As for the FiiO E10, despite it having apparently released many months ago, I'm not aware of reputable USA dealers who have any. A few places, last time I checked, were only accepting "pre orders" but most don't have it listed at all. So I'm not sure when it's going to finally be available.

Resampling from 44 to 48, 96, or 192 can indeed cause audible artifacts. It's best avoided unless you have a very good reason to do it. In my opinion it's a poor choice to design a DAC that cannot natively operate with 99% of available digital music. To me it implies Creative cares more about marketing hype than designing solid hardware.

Resampling from 44.1 to 48 kHz can be made transparent without much load on a CPU that is used in a typical current desktop PC. However, low quality implementations (either as a result of excessive optimization for speed, or simply incompetence) probably do exist, so it is only possible to tell if a particular converter is good enough after testing it.

USB Audio 2.0 is what the industry needed for years. Now it is out, but there are no reasonable priced devices out with it. I tried to find a decent DAC chip with it - no luck, or a USB-I2S converter - lo luck. There are some FPGA implemetation, and ASIC for it but they start from 150$ (just the chip). It would be a miracle, if Texas Instruments, Cirrus Logic or Wolfson would came out with an USB Audio 2.0 device.

Also I found some interesting ASIC which are between USB 1.1 and 2.0, Telenor something, and MU6010, but they got driver problems, and not a "clean" solution for it.

@tzaboo, the vote is still out on USB Audio 2.0. It's so far not at all DIY friendly and some 2.0 products are proving to be very fussy. Check out PSAudio's lengthy page of requirements and suggestions to prevent their high-end USB 2.0 DAC from suffering dropouts. It includes removing other USB devices from your PC, etc. The main 2.0 application so far is for pro audio interfaces used for recording. For that users are willing to configure their PC's around just one use.

Also, just to be clear, you don't need USB Audio 2.0 to get 24/96 over USB with native drivers. The Benchmark DAC1 was one of the first to accomplish 24/96 as a USB Audio 1.X device and now there are several options like those from Centrance. They work very well and arguably better than some of the 2.0 solutions like the one from PS Audio.

Nobody has proven any audible benefit to using 24/192 over 24/96 for playback. In fact, Meyer & Moran even carefully showed how 16/44 could not be distinguished from SACD DSD. There are, however, benefits to 24 bit operation, and at least theoretical benefits to 96 Khz sampling (less phase shift and alias artifacts in the audio band). But there's zero argument based on theory or blind tests for 192 Khz for playback.

So, when you consider all of the above, the only reason to use USB Audio 2.0 is for recording or if you need multi-channel high-res audio. For 2 channel playback it offers no benefit and apparently is much more fussy. I have USB 2.0 audio interfaces but they use proprietary drivers, not the USB Audio 2.0 standard.

@Anon, The E10 isn't just out of stock in the USA, it's not even listed for sale most places. It's not on Amazon or at the Micaa store (I think FiiO largest USA dealer), it doesn't show up in Google Shopping, etc. It's what those in the software business call "vaporware". It would seem FiiO released an initial batch, mostly outside the USA, and something went wrong with producing more.

Apple brings in massive quantities for the launch of their products and product continues to flow to their stores and dealers every week or so even if it does quickly sell out. That's a very different situation than not having any product at all for months as with the E10.

I tried earlier in the week to buy an E10 at the Micca store. Yesterday I pulled up the order details and noticed it was cancelled with a refund. And then the whole item page in their online catalog was gone, like it wasn't available anymore. Still very interested but at least I just received the Audinst HUD-MX1 in the meantime that I am so far happy with.

@Stephan, It's not a PCM2xxx because it lacks the distinctive noise shaping in the ultrasonic region all the TI chips have. Several other measurements are also a bit different. And, finally, the X-Fi also reports supporting 24 bit operation to Windows--something the PCM2xxx can't do. I got your other message about using O2 twice but I can't find the error.

@hotsoup, yes, FiiO seems to be going backwards with the E10. I've noticed the E10 missing from retailers as well. It's very odd. Could FiiO be in trouble?

@Anon, Sorry no internal pics. I'm not sure the X-Fi is designed to be taken apart without destroying it and the one I tested was on loan. There probably wouldn't be much to see besides the likely proprietary chip. Someone, somewhere, might have opened one up and posted pics or a video. If you find anything, please share a link here?

Back to Creative products - which I feel have been underrated by the audiophile community and deserves more highlight - perhaps its time to review Creative's higher-end 'Sound Blaster Digital Music Premium HD' to see how much better it can get. While not big in the US, it is quite popular in Japan. Best of all it goes for under USD100 on Amazon.com so is still within reach to all aspiring audiophiles.

@metalgear, if you're talking about the Creative X-Fi HD 2 channel USB DAC, I was interested in testing one until I found out it supposedly upconverts 44 Khz audio to 48 or 96 Khz and isn't capable of playing it in the native format. I've also heard the headphone output has a relatively high impedance. If anyone has solid information on either of these two issues, please let me know?

I haven't tested the Emotiva XDA1 but I've heard mostly good things about it. Emotiva is sort of the Behringer of home audio. They have really solid engineering and equally solid cheap manufacturing in China. My only caution is I suspect it's on its way out and it should be replaced by a version that can do 24 bit high resolution over USB (which might explain the current discount and "no returns" policy on the XDA1).

The Dacport and HRTs both can do 24 bit over USB so I tend to favor them. Neither, however, has all the cool features the XDA1 does. Any of them will likely run circles around the typical eBay/Asian-designed/cloned DACs like those from Audinst, HA-Info, AudioGD, Matrix, Aune, SMSL, etc. Most of those just seem to throw parts on PC boards and cross their fingers nobody will properly test them.

Wow thanks for the quick response NwAvGuy :)Emotiva it is then. To be honest for its price now I think it's a great deal, and I don't have a great deal of money to spend either :p I can imagine their next model being over $400.

I've never owned a full sized pair of headphones before (650'S arrive 2mo!), and all the dac and amp business is new to me, but I'm sure it'll be a blast for first time experience.

I've been posting over at abi, forever swinging like a mad seesaw deciding on amps and dacs. More than welcome to view the mess I've created over there haha (don't know if you post there?).Now it's down to the amp. o2 or woo audio 3/6. That's what I'm looking over 'there'. Some say I may not want to go tube, o2 has been suggested, but I'm waiting for other possible suggestions as well. For someone who's new to the game I want to be sure and hopefully not spend insane amounts (that's anything over $1000 for me personally).

I bought this product and I must say I'm very dissapointed. It is actually worse than my ALC888 onboard codec.

There is some weird clicking issue in every frequency. Most noticeable in low freq at low software volume (10%). Try to create 1Hz sive wave in Audacity, turn volume up on your amp and you will hear click sound every time it hits max/min apmlitude. It's causing wery bad distortion at every song with more bass. It's notiecable even at max (digital) volume.

Are you sure you have the "Pro" version I tested? If so, it sounds like something might be wrong with yours or you're somehow feeding it a clipped digital signal. The 0 dBFS distortion I measured at 100 hz is respectably low and I didn't hear any such problems in my listening tests. But I no longer have the Go Pro I tested.

Asking any DAC to reproduce a 1 hz sine wave may bring out some unusual behavior as that's essentially a slow moving DC value. Music rarely has much content below 15 hz.

Yes, I have Pro (SB1290). Clicking is present in whole frequency spectrum, most significant in subbass and bass frequencies because it's not masked by high freq. Also clicking frequency is twice as sine frequency. 1Hz clicks twice per second (each amplitude peak). At 50Hz it is 100 times per second so i hear rather buzzing than clicking.

It's weird. Tested on 2 different PC's in two different rooms (windows 7 on both but tried ubuntu linux live CD on my workstation with same issue). Only common thing is that both computers are plugged into APC SurgeArrest P5B-FR.

It should be noted that the "Pro" version of the X-Fi Go! is inferior to the regular version, in both hardware and software. I was hoping the regular Go! was tested, as the "Pro" is quite awful, and most batches around the world have significantly higher hissing compared to the regular Go!. Also, Go! Pro does 16/44 and 24/44 while the regular Go! does 16/44.1, 16/48, 24/44.1 and 24/48.

I know you say it doesn't have enough power to drive the HD-600, but I have to disagree. I've been listening to this combination for the last few hours without any complaints. I also have two other desktop amps for comparison.

There is no lack of volume and it even sounds good! No issues with bass or lack of soundstage. It's actually a nice match for the HD-600. Now I certainly don't suggest it for a primary amp, but for travel use, it would get the job done.

One person's idea of "lack of volume" can be very different than another person's. As explained in my More Power article, personal preference, and the type of music listened to, can make a 10 dB or even greater difference in power requirements. That's relatively huge. So for some the X-Fi might have enough output with the HD600, for others it won't.

The only way I can be objective about headphone/amp compatibility is to use an accepted methodology that takes into account typical peak listening volumes, the device's power output, and the headphone sensitivity. By that criteria, the X-Fi falls short with the HD600. The methodology is described in detail in the More Power article for those who are curious.

I have the shure-SRH440, do you recon the Creative go pro X-FI, would be a good match or may be the U3, I am not an audio philly ex 128KB/s Listener. I think any of these should be better then onbard lappy audio?. well I have found out my laptop has an SNR 95 and that X-FI has SNR 97, so maybe better.

do you guys recomend the X-Fi for the Shure SRH440 or maybe the Asus U3 but it sugests the X-Fi as the Impedance is quite low for big ear phones 44ohms is the SRH440 impedance. my laptop has an Realtek ALC888 HD Audio which has an SNR/95 I hear the X-Fi is around SNR/97. I am not loaded and no audio philly I come from a back-ground of listining to 128Kb/s mp3s.

PLEASE NOTE! If you see "LOAD MORE..." OR "LOADING..." just above this paragraph, you need to click that link to load the newest comments. It may take several seconds. When all the comments are displayed the Load More/Loading link disappears.

COMMENT APPROVAL: Comments may take anywhere from a few minutes to a few days to be approved. You might want to save a copy (highlight Ctrl-C) of your comments before submitting in case something goes wrong. The approval process is necessary to prevent obscenity, etc. Please keep comments on topic. Comments promoting commercial interests will not be approved and may be reported as SPAM.